<!DOCTYPE html>
<html lang="en">

<head>
    <title>html5</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1"> </head>

<body>
    <math xmlns="http://www.w3.org/1998/Math/MathML">
        <mrow>
            <msup>
                <mi>a</mi><mn>2</mn>
            </msup>
            <mo>+</mo>
            <msup>
                <mi>b</mi><mn>2</mn>
            </msup>
            <mo>=</mo>
            <msup>
                <mi>c</mi><mn>2</mn>
            </msup>
        </mrow>
    </math>
</body>

</html>